Organic scintillators

ABSTRACT

ORGANIC SCINTILLATORS HAVING RELATIVELY HIGH SOLUBILITIES IN HOMOPOLAR SOLVENTS, COMPRISING A VARIETY OF SUBSTITUTED OLIGOARYL COMPOUNDS.

United A States Patent Olfice 3,600,445 Patented Aug. 117, 1971 US. Cl. 260-613 2 Claims ABSTRACT OF THE DISCLOSURE Organic scintillators having relatively high solubilities in homopolar solvents, comprising a variety of substituted oligoaryl compounds. 7

This invention relates to oligoaryl compounds and, in particular, to the use of such compounds in scintillation counters.

Liquid and plastic scintillators are of increasing economic importance as radiation detectors. They are used primarily for the detection and the examination of radioactive substances, for the detection of elementary particles and quanta, and for the determination of their nature, energy, and lifetime.

The mode of action depends upon the fluorescence phenomenon. Passing through the activated state, a quantity of photons is formed in proportion to the quantity of primary radiation. These photons can then be registered photo-electrically, for example, by a photomultiplier tube. This method of counting is now of considerable technological significance, particularly in the examination of weak emitters of B-rays, such as C and H The device employed is known in the art as a scintillation counter.

A compound to be used as a scintillator must possess a high light output and be readily soluble in certain solvents, such as preferably alkyl aromatics or vinyl polymers thereof. A substance which does not dissolve is unusable for this purpose, no matter how high its light output.

The scintillators normally used heretofore are paraterphenyl, 2,5-diphenyloxazol (PPO), and 2,5-bis[5'- tert.-butyl-benzoxazolyl-(2)]-thiophen (BBOT). Methylor methoxy-substituted oligophenylenes have also been suggested for this use, but their solubility is not satisfactory. Their synthesis is, for example, described in Makromolekulare Chemie, vol. XXIX, p. 164.

All of these fluorescent materials have difficulties on practical application. They have either a relatively low light output or too poor a solubility in the solvents customarily employed for this application. That 2-(4-biphenylyl)-5-phenyloxadiazol (PBD) has not been more widely introduced in practice even with the highest light output yet attained is due to its insufficient solubility. Those compounds With heterocyclic rings which were used up to now as scintillators have the additional disadvantages that they are not only unstable to radiation, but also their chemical and thermal stability leaves much to be desired.

An object of this invention, therefore, is to provide organic scintillators having improved properties.

Another object of this invention is to provide novel chemical compounds and their methods of manufacture.

A further object is to provide improved articles of commerce, such as paints, lacquers, and detergent compositions, based on the organic scintillators of this invention.

Upon further study of the specification and claims, other objects and advantages of the present invention will become apparent.

To attain the objectives of the invention, there are provided organic scintillators which not only are very readily soluble but also have a good, and sometimes an extraordinarily high, light output and which, in addition, are characterized by a remarkable chemical stability towards radiation.

These organic scintillators are oligoaryl compounds of Formula I, as follows:

@[@1 wherein n is an integer from 0-16;

A, B, and C represent conjugated phenyl or naphthyl radicals, of which at least one is substituted by at'least one R;

R is straight or branched and represents saturated or unsaturated alkyl or alkoxy radicals with 142. carbon atoms which, if desired, can be interrupted with oxygen atoms and/or can be substituted with R or R can represent R and R is a phenyl, biphenyl, naphthyl, or cycloaliphatic ring with 512 carbon atoms substituted, if desired, with lower alkyl or alkoxy groups;

with the provision (a) That n shall not represent zero if A and B are phenyl rings,

(b) That if R is an aromatic radical, it shall not be arranged in the para-position of the rings A and/or B,

(c) That the oligophenylene compounds are not substituted solely by methyl or methoxy groups,

(d) That a substitution with R in the ortho-position to a biaryl bond is only permissible if within the entire oligoaryl compound there are at least 3 aromatic rings conjugated with each other and which are (1) either unsubstituted, or

(2) substituted only once at such position, and if so substituted, at least one of rings A and B must also be substituted in the para-position.

There are particularly useful subgeneric groups embraced by Formula I. For example, good success is achieved with para-terphenyl of Formula II III wherein R and R have the previously indicated significance.

Para-quaterphenyls of Formula IV I O O O O 1v wherein R has the previously indicated significance and means the same or different radicals, have also been recognized as very valuable scintillators.

In addition to the aforesaid specific subgeneric groups, the para-quinquiphenyls of Formula V are also important wherein the radicals R can also be the same or different and have the above-mentioned significance.

Moreover, binaphthyl compounds of Formula IV are highly useful, as follows:

wherein R and R have the above-mentioned significance. Still further, the para-quinquiphenyls of Formula VII are also of considerable interest, wherein the substituents R are the same or different and have the above-mentioned significance.

Furthermore, the compounds of Formula IX are also suitable, or even those of Formula X O O o o o o wherein R and/or R have the previously indicated significance.

Also of significance are the compounds of Formula XI or of Formula XII R i XII wherein R has the previously indicated significance.

In addition, the compounds of Formula XIII RH2O\ R-CH should also be mentioned, wherein the radicals R have also the above-mentioned significance,

The compounds of the said Formulae I-XIII can be even further substituted by additional R radicals. In particular, one or more substitutions in the following positions are preferred (nomenclature, see Makromolekulare Chemie [Macromolecular Chemistry], vol. 29, 1959, p. 167):

For compounds of Formula II: 1 1 3 3 For compounds of Formulae III and XIII: 1 1 4 4 4 For compounds of Formula IV: 1 1 4 4 For compounds of Formula V: 1 1 1 5 5 5 For compounds of Formulae VI and X: 3,3; 7,7; 8,8; if desired, also in 6 and/or 6'.

'For compounds of Formula VII: 1 1 1 5 5 5 For compounds of Formula VIII: 1 1 1 2 2 5 5 6 6 6'.

For compounds of Formula 1X: 1 1 1 3 3 For compounds of Formula XI: 1 1 1 4 4 For compounds of Formula XII: 1 1 1 1 2 2 5 5 6 6 6 6 The oligoaryls to be used as scintillators according to this invention are thus ring assemblies of aromatic com pounds which are composed of several phenyl and/or naphthyl rings directly connected with each other. It is of fundamental importance in this connection that the aromatic rings are disposed in conjugation to each other. The phenyl rings must thus be bound, through the 1,4- position, whereas it is possible for the naphthyl rings to be connected through the preferred 1,4- and the 2,6- positions. The connection of the naphthyl rings through the 1,2-position, which is also possible, is less favorable owing to steric hindrance of resonace.

As can be seen from the above formulae, not only oligophenylenes and oligonaphthylenes, but also such compounds wherein phenyl rings alternate with naphthyl rings in any sequence whatsoever can be used according to the present invention.

If only naphthyl rings are present in the molecule, n preferably represents 0-4. If phenyl and naphthyl rings alternate with one another, then n is preferably 0-8. In oligophenylenes, n can preferably represent any integer from 1 to 16, inclusive.

In these compounds, at least one of the aromatic rings must be substituted. The higher oligoaryls, without such substitutions, are so slightly soluble that they cannot be used as scintillators, although they are quite satisfactory with respect to obtainable light output. It is, therefore, advantageous for the solubility of the oligoaryls to 'be not less than 10 g./l. toluene at 20 C. For the oligoaryl compounds with a higher degree of condensation, i.e., more than 4 rings, generally more (at least 3) or longer R groups are required to achieve the necessary solubility, it being preferred, in this connection, to employ at least 3 R groups or at least one R group containing at least 6 carbon atoms.

It has now been found that readily soluble substances are obtained if the rings A, B, and/or C are substituted not only 'by methyl or methoxy but, in place of or in addition to these, by one or more R substituents. In general, particularly valuable substances are obtained if longer-chain (i.e., at least 4 carbon atoms), particularly branched, substituents are present. The eflicacy of the R substituents is highest if the molecular symmetry of the total molecule is disturbed, or if the bulk (specific volume) of the total molecule is increased. Furthermore, the higher the internal molecular mobility of the R group, the better the solubility of the total molecule, all other things being equal.

Surprisingly, substances of the prior art which are only substituted by methyl or methoxy groups do not fulfill the requirements demanded of a scintillator, whereas corresponding ethyl derivatives are most suitable. Thus, for example, the 1 ,5 dimethyl para quinquiphenyl (for nomenclature see Makromolekulare Chemie, vol. 29, p. 164, 1959) has a solubility of only 1.3 g./l., whereas that of the corresponding ethyl compound was found to be 24 g./ 1.

The most important contribution of the R substituents is that they give the oligoaryls an increased solubility. They also simultaneously counteract the concentration extinction of the fluorescence, which amounts to an additional gain in light output. The optical properties of these compounds remain on the whole uninfluenced by the constitution of the R radical. It is therefore relatively unimportant, particularly in the case of longer-chain R substituents, which individual substituents are present in the chain. Of course, extinguishing groups, such as N SH, S, NH NH, N COOH, or OH should be avoided, if possible. Otherwise, only gradual changes in the solubility appear through the various substitutions, particularly in longer chains.

As far as the position of the substituents is concerned, it has proved to be particularly advantageous to arrange these in such a way that the coplanarity of the oligoaryl system is not disturbed. Particularly advantageous substituents are those in the para-positions and/or in the ortho-positions thereto of rings A and/or B. Substituents in the ortho-positions to a diaryl bond (in the rings A, B, and/or C), on the other hand, always impair the conjugation of the oligoaryl system so that the light output is decreased, particularly in compounds with only few rings. Areas of interference of particular intensity which influence the conjugation of the system unfavorably are, for example, two substituents at two adjacent aryl rings which flank one and the same biaryl bond. If a quaterphenyl, for example, contains an area of interference (e.g. substituents in the ortho-position to a biaryl bond between two adjacent rings), compensation must be achieved by the substitution of the rings A and/or B with an auxochrome in the para-position(s). If both parapositions are substituted by auxochromic groups (e.g. longer-chain, preferably branched alkoxy groups), then further substituents in the ortho-position can still be permissi'ble. These substituents should, however, preferably not be too bulky, i.e., for example, should not possess any secondary or tertiary carbon atom bound directly to a ring. Furthermore, substituents on adjacent rings which jointly flank the biaryl bond situated between them should generally not be too bulky.

The light output is generally particularly good if an undisturbed conjugated system of at least three aryl rings or a quaternary system impeded by only one area of interference is present. These systems in and of themselves can, of course, occur at one or more various positions of a larger oligoaryl system, and then are not required to be disposed in conjugated form to one another. Naturally, in the case of the polynuclear aryl systems, the areas of interference have an ever lessening influence, decreasing with the number of rings in the scintillator.

Normally, there are not more than 16 R substituents in the oligoaryl compounds according to the present invention. Preferably, the number of R substituents is between 2 and 6.

The R substituent can be a straight or branched, saturated or unsaturated alkyl or alkoxy group with 1-42 carbon atoms which, if desired, can be interrupted by oxygen atoms and/or substituted by R Furthermore, R can also represent R but this substituent cannot then be arranged in the para-position of rings A and/or B if it is an aromatic radical. R is a phenyl, biphenylyl, naphthyl, or cycloaliphatic ring with -12 carbon atoms substituted, if desired, by lower alkyl or alkoxy groups.

Besides the lower alkyls, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert.-butyl, n-amyl, or isoamyl, other suitable groups are also the higher homologs, such as hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, as well as their isomers and homologs with up to 42 carbon atoms, or the corresponding alkoxy groups. Branched radicals, such as, for example, 2-ethylhexyl, 2- butyloctyl, 2-hexyldecyl, 4-methylamy1, 4-methyl-2-prob pyl-l-pentyl, 2,2,4-trimethyl-l-pentyl, -phenylpropyl, 2,2- dimethylpentyl, 2,2-dimethylbutyl, 2,2-dimethy1hexyl, 2,2- dimethylpropyl, a-tolylbutyl, B-cyclohexylbutyl, hexahydrofarnesyl, tetrahydrogeranyl, or dihydrophytyl are particularly favorable.

The alkyl and alkoxy radicals can also be unsaturated, i.e., contain one or more, preferably 1-2 double bonds. If several double bonds are present in the R substituents, it is advisable to have them non-cumulative. It is advantageous, moreover, if one or two of these isolated double bonds stand in conjugated disposition to the oligoaryl system. Such a double bond functions as an auxochromic group. From the great number of possible unsaturated alkyl (or the alkoxy radicals derived therefrom), there are mentioned, for example: butenyl, 3-methyl-butene- (3)-yl-(1), hexenyl, heptenyl, nonenyl, undecylenyl, tridecylenyl, heptadecylenyl, 2,8-dimethyl-nonatriene(1,4,8)- yl, phytyl, geranyl, farnesyl, and. untetracontene(20)-yl- (21).

The use of long-chain branched alkyl or alkoxy radicals, e.g. from the Guerbet series or from the group of the isoprenoids, is often of particular advantage. In these cases, the starting materials are particularly easily accessible.

The alkyl or alkoxy radicals can be interrupted with oxygen atoms at random positions. These oxaalkyl or oxaalkoxy radicals can also contain up to 42 chain atoms. The following are mentioned only as examples: 3-mothoxybutyl, 4-ethoxypentyl, 3-oxaamyl, 3,6,9-trioxaundecyl, 3,6-dioxaoctyl, 3,6,12,15 -tetraoxaheptadecylene- )-y If more than two oxygen atoms are contained in the R substituents, a particularly favorable arrangement is to have the oxygen atoms each between two carbon atoms (-O-C-COC-CO). Such compounds can be prepared particularly well from ethylene oxide. Thus, it is preferred that the maximum number of oxygen atoms be not more than about one-half the number of carbon atoms in the chain. The terminal hydroxy group which inay form primarily is preferably etherified, i.e. methylated.

For the R substituents, cycloaliphatic rings containing 5-12 carbon atoms are preferred radicals, e.g., cyclopentyl, cyclohexyl, bicyclohexyl, and decahydronaphthyl. On the other hand, suitable aromatic radicals are, for example, phenyl, biphenylyl, and naphthyl. All of these rings can, in turn, be substituted by lower alkyl or alkoxy groups, preferably by methoxy, ethoxy, propoxy, butoxy, or amyloxy, or methyl, ethyl, propyl, butyl, or amyl. As preferred examples, the following are set forth: Z-methylcyclohexyl, 2,5-dimethylcyclohexyl, 2,3-dimethoxy-decahydronaphthyl, tolyl, xylyl, and 3,5-dipropoxyphenyl.

Some specific examples of the compounds of this invention are, for instance, the following:

1 ,4 -bis- [2-butyloctyloxy- 1) ]-p-quaterphenyl,

4,4-bis- [n-octyloxy-( 1 ]-1, l'-binaphthyl,

4,4'-bis-(oxaamyloxy)-1,1'-binaphthyl,

4,4-bis-(dioxanonyl)-1,1-binaphthyl,

1 ,4 -bis- [S-nonene (4) yl] -p-quater phenyl,

1 ,4 -bis- [7-tridecylene( 6 yl] -p-quaterphenyl,

1 ,4 -bis- [2 1 -untetracontene 20 yl] -p-quaterphenyl,

1 ,5 -bis- [3 ,6,12,15-tetraoxa-9-hepta-decylene(8)yl]-pquinquiphenyl,

1 [2-ethylhexyl-( 1 ]-4 -phenyl-p-quaterphenyl,

1 [2-butylcetyloxy-( 1) ]-3 -biphenylyl- (4) -p-terphenyl.

Typical structures of the oligoaryl compounds of the present invention which are to be substituted as defined above are, for example, the following:

The new compounds according to the present invention are prepared by processes known per se. A useful method of synthesis is, for example, the organometallic carbonyl reaction (Makromoelekulare Chemie, vol. 29, p. 164, 1959), in which the organometallic compounds of the oligoaryls are reacted with cyclic or oligocyclic monoor diketones. This reaction is followed by a dehydrogenation and aromatization.

The new compounds can be more easily prepared by the biaryl condensation reaction according to Ullmann (Makromolekulare Chemie, vol. 63, p. 30, 1963). In this reaction, aromatic iodo compounds are joined by eliminating the halogen by means of copper powder. By the addition of catalytic amounts of mercury, an increase in the yield can be achieved. The iodoaryls necessary for this reaction are particularly easily produced by direct iodization using iodine/iodic acid (see Liebigs Annalen, vol. 643, p. 84, 1960). This method also includes the possibility of using the lower homologs as starting materials in the synthesis of the higher homologs.

The preparation of the higher arylhomologs is achieved with the aid of the co-condensing Ullmann reaction (Makromolekulare Chemie, vol. 63, p. 32, 1963). The stoichiometric conditions can be so chosen to produce the preferred higher homologs. The separation of each homolog in the formed mixture is possible by preparative layer chromatography.

The R substituents can be present in the starting products or can be introduced following the formation of the oligoaryl system. In the case of the polynuclear compounds, it is to be recommended for reasons of solubility that the desired R substituents be introduced before the aryl condensation reaction.

There are two principal methods for the introduction of the R substituents. First, there is the etherification of OH groups at the oligoaryl system with the aid of the corresponding sulfonic acid ester. Thereby, compounds are formed in which R represents an alkoxy radical. Second, the reaction of oligoaryls containing carbonyl or carboxyl groups with organometallic compounds permits the introduction of such substituents in which R repre sents an alkyl radical or R The carbinols formed first in this reaction can, for example, be converted to saturated alkanes by treatment with hydrogen iodide and red phosphorus. If only a dehydration is undertaken, for example by treatment with oxalic acid in dioxane, the corresponding a-olefins are obtained. In certain cases, the C-C bound radicals can also be introduced through the known nuclear alkylation reaction with Lewis acids (e.g., AlCl BF ZnCl wherein the corresponding olefins, halogenides, or alcohols can be used.

Those compounds according to the present invention which contain oxaalkyl groups, possess not only the essential solubility in homopolar solvents but also a certain solubility in water. This property is of great advantage, for example, in the examination of aqueous specimens (for instance water containing tritium).

A whole series of compounds according to this invention also possess an extremely high solubility, which allows highly concentrated or over-saturated solutions to be prepared from them-a great advantage with respect to measuring problems. In some cases, the compounds are even oils which are miscible to an unlimited degree with homopolar solvents (non-polar solvents). They are described in more detail, for example, in US. patent specification 3,148,194.

The particularly short decay period of the new compounds is very favorable for many measurements, particularly for particle discrimination. The decay periods of the fluorescence are reduced as the degree of condensation is increased.

The suitability of the new compounds of the present invention as scintillator solutes was checked by an approved test method (U.S. Report LA. 2176, 1958, or Zeitschrift fuer Elektrochemie, Berichte der Bunsen- Gesellschaft, vol. 64, page 1098, 1960). Stimulation is carried out by ,8-radi'ation. The relative light output 1, thus measured was based on 2,5-diphenyloxazol (PPO) whose solution in toluene of 3 g./l. is fixed to be the relative value 1.00. The light outputs I for a whole series of the new compounds are considerably higher than those of PDB [2-(4-biphenylyl)-5-phenyl-oxadiazol], the light output (I '=1.28) of which could not be surpassed previously. The light output increases along with the degree of condensation (increasing values for n). In addition to this, the relative yields of fluorescence of the new compounds on UV stimulation were determined with the aid of a spectrophotometer.

The compounds according to the present invention can be used in many ways as a result of their scintillator properties. When used in scintillation counters, they are employed in combination with a transducer for converting light energy into electrical energy, and preferably with a photomultiplier tube. Such use entails a process comprising exposing the scintillator substance to a source of 04-, [3- or also 'y-rays, to produce photons, and then converting such photons into electrical energy. General properties of such scintillators and their use as counting media are, for example, largely described in U .S. patent specification 3,148,194. The details as given in this specification also apply to the compounds of the present invention.

Besides their suitability as radiation detectors, they are particularly suited to particle spectroscopy, because of the short decay time of the luminescence. Furthermore, they can be introduced into protective coatings, such as lacquers and paints (scintillation lacquers). These can be applied to equipment and appliances which are used in association with radioactive substances. By this means, even minimal contamination with radioactive materials can be detected. If desined, wave length shifters can be added to these scintillation lacquers in order to shift the emission further into the visible range. In the case of the higher homologs, wave length shifters are not necessary.

In radioscopy, an increase in contrast in the X-ray plate can be achieved by the addition of the scintillators according to the invention, thus allowing the time of exposure to be shortened. A further field of application for the new compounds is to be found in their use as optical bleaches. As is already known, the yellow discoloration occurring on the ageing of artificial and natural fibers can be made to disappear by the admixture of blue fluorescent substances. Those compounds of the present application which contain long branched alkyl radicals also display plasticizer properties. Thus, by using those compounds, textile adjuvants are available wherein two valuable properties are combinednamely, a plasticizer effect and an optical bleach effect.

Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The following preferred specifio embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the specification and claims in any way whatsoever.

In the following examples, the symbol S represents solubility in toluene at 20 C.

EXAMPLE 1 2.46 g. of l -hydroxy-p-terphenyl (Journal Chemical Society [1939], p. 1283) are dissolved in the least pos sible hot alcohol and then combined with an alcoholic solution of 1.2 g. of potassium hydroxide. Following the addition of 4.9 g. of benzenesulfonic acid-2-butyloctylester, it is heated at reflux for 5 hours. The alcohol is largely distilled off and the residue subsequently worked up with water/ether. Purification is carried out by dissolution in benzene and chromatography over a column loaded with a mixture of calcium chloride, calcium oxide, and aluminum oxide. The resultant 1 -[2-butyloctyloxy- (1)]-p-terphenyl is a viscous oil which is miscible with all homopolar solvents in every proportion.

The following are similarly prepared:

l [2-hexyldecyloxy-(1)J-p-terphenyl; oil; 5: oo 1 [2- 3 -oxaamyl)-5-oxaheptene-1-yloxy-(1) ]-pterphenyl 1 -[2,2,4-trimethylamyloxy-(1)]-p-terphenyl 1 [2-ethylbutyloxy-(1)]-l -methyl-p-terphenyl EXAMPLE 2 2.62 g. 1 ,3 -dihydroxy-p-terphenyl (Journal American Chemical Society, vol. 66 [1944], p. 632) are added to a solution of 2.3 g. potassium hydroxide in 50 ml. diethylene glycol, and dissolved by heating to about 150 C. Following the addition of 8.1 g. of benzenesulfonic acid- Z-ethylhexylester, the solution is heated for a few minutes to almost 200 C. Working up is done with water and ether. Purification is carried out by chromatographing the solution of the raw product in benzene over a mixture of pulverized potassium hydroxide and aluminum oxide and subsequently recrystallizing from ether/methanol. 1 ,3 bis-[2-ethylhexyloxy-(1)]-p-terphenyl with a melting point of C. is obtained. S=2195 g./l.

The following are similarly produced:

1 ,3 bis (hexahydrofarnesyloxy)-p-terphenyl, M.P. 109 C., S=72 g./l.

1 ,3 -bis-(dihydrophytyloxy)-p-terphenyl, M.P. 94 C. 8:160 g./l.

1 ,3 bis [3-(3,5 dioxaoctyl)-6,9-dioxaundecene-3- yloxy-( 1) ]-p-terphenyl; oil; S: 00.

1 ,3 bis-[2-butyloctyloxy-(1)]-p-terphenyl.

1 ,3 -bis- 2-hexyldecyloxy( 1 ]-p-terphenyl.

1 ,3 dimethyl 1 ,3 -bis [2-ethylbutyloxy-( 1)]-pterphenyl.

1 ,3 dimethyl 1 ,3 bis [2,2,4-trimethylpentyloxy- (1)]-p-terphenyl.

EXAMPLE 3 (a) 11.2 g. potassium hydroxide are dissolved in as little ethanol as possible. This solution is combined with the hot solution of 30 g. 4-iodo-4-hydroxybiphenyl (Journal American Chemical Society, vol. 66 [1944], p. 491) in ml. ethanol. Following the addition of 36.3 g. benzene-sulfonic acid 2 butyloctylester, the mixture is boiled at reflux for 5 hours; subsequently, the alcohol is largely distilled off. Working up is carried out with water/ methylene chloride. The 4-iodo-4'- [2-butyloctyloxy-(1)]- biphenyl is obtained in the crystalline form from ether/ methanol; M.P. 67 C.

(b) 17.7 g. 4-iodo-4-[2-butyloctyloxy-(1)]-biphenyl, 15 g. copper powder, and 3 drops mercury are heated in a suitable reaction vessel (Makromolekulare Chemie, vol. '63, 1963, p. 30) for 2 hours at 200 C., 2 hours at 220 C., and 1 hour at 240 C. The reaction mixture is extracted with petroleum ether; subsequently, the 1 ,4 bis-[2-butyloctyloxy-(1) ]-p-quaterphenyl is recrystallized from petroleum ether and ether/methanol (each time cooling to 30 C.); M.P. 163 C., S=63 g./l.

The following are similarly produced:

1 ,4 bis [2-ethylhexyloxy-(1) ]-p-quaterphenyl, M.P. 231 C., S: 10.3 g./l.

1 ,4 bis [2-hexyldecyloXy-( 1 ]-p-quaterphenyl, M.P. 135 C., S=370 g./l.

1 ,4 -bis-[2 (3-oxaamy1)-5-oxaheptene-1-yloxy-(1)]- p-quaterphenyl.

1 ,4 -tetraethyl-1 ,4 bis [2-ethylbutyloxy-(l)]-pquaterphenyl.

1 ,4 -tetra-terL-butyl-1 ,4 bis [2,2-dimethylpropyloxy- 1 ]-p-quaterphenyl.

EXAMPLE 4 26 g. 3-(tert.-butyl)-iodobenzene (Journal Chemical Society [1928], p. 2338), 4.1 g. 4,4-diiodobiphenyl, 27 g. copper powder, and 5 drops of mercury are heated, as in Example 3(b), for 3 hours at 200 C. and 2 hours each at 230 C. and 250 C. The reaction mixture is extracted with petroleum ether. Following removal of the solvent, the 1 ,4 -bis-(tert.-butyl)-p-quaterphenyl results in the crystalline form on the addition of methanol. Purification is carried out by chromatographing over aluminum oxide charged with hydrochloric acid and then recrystallizing twice from petroleum ether. M.P. 196 0., 8:52 g./l.

EXAMPLE 5 (a) The Grignard solution consisting of 83 g. n-bromopentane and 13 g. magnesium chips in ether is reacted with the ethereal solution of 93 g. m-iodobenzaldehyde. The (3-iodophenyl) n pentylcarbinol thus formed is worked up in the usual way. Boiling point 123- 125 C.

90.5 g. (3-iodophenyl)-n-pentylcarbinol are refluxed for 18 hours with 70 ml. hydriodic acid (spec. grav. 1.70) and g. red phosphorus. After working up with methylene chloride/ water, the 3-(n-hexyl)-iodobenzene is purified by double distillation. Boiling point 81'83 C.

'(b) 26 g. 3-(n-hexyl)-iodobenzene, 3.7 g. 4,4'-diiodobiphenyl (Liebigs Annalen Chemie, vol. 634 [1960], p. 84), 24 g. copper powder, and 3 drops of mercury are heated for 3 hours at 200 C. and 2 hours each at 230 C. and 250 C. Following extraction with benzene, the 1 ,4 bis-(n-hexyl)-p-quaterphenyl is separated by distillation. Purification is carried out by chromatographing over aluminum oxide charged with hydrochloric acid; the compound is finally recrystallized from ether/methanol and from petroleum ether; M.P. 157 C., S=46 g./l.

The following are similarly prepared:

1 ,4 bis- (n-butyl)-p-quaterphenyl, M.P. 165 G, 5:43 g./l.

bis (n-octyl)-p-quaterphenyl, M.P. 150 G, 8:48 g./l.

1 ,4 bis (Z-propyl)-p-quaterphenyl; M.P. 166 C., S=10O g./l.

1 ,4 -bis-[3,3,5-trimethylhexyl-(1) ]p-quaterphenyl.

1 ,4 -bis-[3,3-dimethylbutyl-( 1 ]-p-quaterphenyl.

1 ,4 -bis-[3-phenylpropyl-( 1) ]-p-quaterphenyl.

EXAMPLE 6 (a) The Grignard solution consisting of 193 g. 2,2,4- trimethyl-bromopentane-( 1) and 25 g. magnesium chips in ether is reacted with the ethereal solution of 135 g. 4-iodobiphenyl-carboxylic acid-(4)-methylester (Makromolekulare Chemie, vol. 68 [1963], p. 92). The (4'- iodo)-biphenyl-'(4) bis [2,2,4-trimethylamyl-(1)]-carbinol thus formed is dehydrated with oxalic acid in dioxane (Makromolekulare Chemie, vol. 42 [1961], p. 179) to 2,4,4,8,8,10-hexamethyl-6-[(4'-iodo)-biphenylyl- (4)]-undecene-5-yl. The non-crystallized compound is purified by molecular distillation at 200 C. and 10- mm. Hg.

(b) 30 g. of the iodo compound obtained according to Example 6(a) are reacted with 25 g. copper powder and 3 drops of mercury, as described in Example 3(b). Following extraction using petroleum ether, the 1 ,4 -bis- [2,4,4,8,8,10 hexamethylundecene 5 yl (6)]-pquaterphenyl is purified by fractional precipitation. A product of waxy consistency, without a precise melting point and with extremely high solubility is obtained.

The following are similarly prepared:

1 ,4 bis [3,3,7,7 tetramethylnonene-4-yl-(5)]-pquaterphenyl.

1 ,4 bis [3,6,12,1S-tetraoxaheptadecene-8-y1-(9)]- p-quaterphenyl.

1 ,4 bis [1,5-diphenylpentene-2-yl-(3)]-p-quaterphenyl.

1 4 bis [1,3 dicyclohexylpentene-2-yl-(3)]-pquaterphenyl.

EXAMPLE 7 (a) 11.5 g. p-terphenyl are reacted with 5 g. iodine and 2 g. iodic acid in a mixture of 120 ml. glacial acetic acid and 8 ml. sulfuric acid with stirring at C. The l -iodo-p-terphenyl is purified of the accompanying diiodo derivative and starting product by fractional crystallization from xylene, M.P. 245 C.

(b) 18.3 g. 3-(tert.-butyl)-iodobenzene, 5.4 g. 1 -i0dop-terphenyl, 20 g. copper powder, and 5 drops of mercury are heated for 3 hours at 200 C. and for 2 hours each at 230 C. and 250 C. The reaction mixture is extracted with benzene, the raw product digested with methanol and the remaining residue distilled in vacuum. This is followed by a chromatographic purification over aluminum oxide charged with hydrochloric acid. The crystalline 1 (tert.-butyl)-p-quaterphenyl is obtained from ethyl acetate/methanol; M.P. 206 C., S=11.7 g./l.

The following are similarly obtained:

1 -(5-nonyl)-p-quaterphenyl.

1 [3-(3,6-dioxaoctyl)-6,9-dioxaundecene-3-y1-(1)]- p-quinquiphenyl.

EXAMPLE 8 23.2 g. l-iodoethylbenzene (Journal praktische Chemie, vol. 81 [1910], p. 559), 4.8 g. 1 ,3 -diiodo-p-terpheny1, 27 g. copper powder, and 5 drops of mercury are heated for 3 hours at 200 C. and 2 hours each at 230 C. and 250 C. The reaction product is extracted with benzene and then treated with methanol in order to remove the biphenyl derivative formed as a by-product. The 1 ,5 -diethyl-p-quinquiphenyl is isolated by distillation. Purification is carried out by chromatographing in benzenic solution over aluminum oxide charged with hydrochloric acid. Following double recrystallization from petroleum ether and ethyl acetate/methanol, the pure compound is obtained, M.P. 180 C., S=24 g./l.

EXAMPLE 9 (a) The Grignard solution of 193 g. n-octylbromide and 25 g. magnesium chips in ether is reacted with an ethereal solution of 105 g. m-iodobenzoic acid methyl ester (Zeitschrift physikalische Chemie, vol. 24 [1897], p. 244). The carbinol thus formed is, without further purification, refluxed for 18 hours with ml. hydriodic acid (spec. grav. 1.70) and 12 g. red phosphorus. Working up is done with methylene chloride/water; finally, the 3 (9 heptadecyl)-iodobenzene is double distilled. B.P. 157160 C.

(b) 28.7 g. p-terphenyl is reacted with 25 g. iodine and 10 g. iodic acid in 400 ml. glacial acetic acid and 25 ml.

sulfuric acid at 80 C. with stirring. The 1 ,3 -diiodopterphenyl filtered off after cooling is pure enough for further reaction. 'Recrystallized from dichlorobenzene, the diiodo compound has a precise melting point of 319 C.

(c) 39 g. 3-(9-heptadecyl)-iodobenzene, 9.6 g. 1 ,3 -diiodo-p-terphenyl, 30 g. copper powder, and 5 drops of mercury are reacted and worked up as described in Example 5'(b). The biphenyl derivative formed as a by-prodnot is removed by distillation. The residue remaining is separated by preparative layer chromatography. In addition to the 1 ,5 bis (9-heptadecyl)-p-quinquiphenyl (M.P. 80 C., S 500 g./l.) which is obtained as the main product, another three higher homologs are isolated:

l ,8 -bis- (9-heptadecyl -p-octylphenyl,

1 ,1 1 -bis- (9-heptadecyl) -p-undecipheny1, and

1 l 4 -bis-(9-heptadecyl) -p-tetradeciphenyl.

Identification is carried out by spectroscopy.

The following are similarly obtained:

1 5 bis-(S-nonyl)-p-quinquiphenyl, M.P. 177 G, 8:34 g./l.

1 ,5 -bis-(7-tridecyl)-p-quinquiphenyl, M.P. 127 C., 5:227 g./l.

1 ,5 bis [2, 4,4,8,8,10 hexamethylundecyl-(6)]-pquinquiphenyl.

EXAMPLE 10 A well stirred mixture of 44.2 g. 3-(9-heptadecyl)-i0dobenzene, 20.3 g. 4,4-diiodobiphenyl, g. biphenyl, 38 g. copper powder, and 5 drops of mercury is heated for 3 hours at 200 C. and for 2 hours each at first 230 C. and then 250 C. The reaction mixture is extracted with benzene. The 3,3'-bis- (9'-heptadecyl)-biphenyl formed as a by-product is separated by distillation along with the biphenyl used assolvent. The remaining residue is separated by preparative layer chromatography. The resultant 1 ,4 bis-(9-heptadecyl)-p-quaterphenyl has a waxy consistency with no precise melting point and is extremely readily soluble in homopolar solvents. 0f the higher homologs, the 1 ,6 -bis-(9-heptadecyl)-p-sexiphenyl, the l ,8 -bis-(9- heptadecyl -p-octiphenyl, the 1 ,10 -bis-(9-heptadecy1) -pdeciphenyl, and finally the 1 ,12 -bis-(9-heptadecyl)-pduodeciphenyl can be obtained and spectroscopically identified.

EXAMPLE 11 A hot solution of 2.86 g. 4,4-dihydroxy-1,1-binaphthyl (Chemische Industrie 10 [1887], 98) in ethanol is purified with a highly concentrated solution of 2.3 g. potassium hydroxide in ethanol. Following the addition of 8.1 g. benzenesulfonic acid-n-octylester, the mixture is refluxed for 5 hours; then the alcohol is largely distilled off. The precipitation of the alkylether is completed by the addition of water. Purification is carried out by chromatographing in benzene over a mixture of powdered potassium hydroxide and aluminum oxide; finally, the 4,4-bis- [n-octyloxy (1)]-1 ,1'-binaphthyl is recrystallized once more from ethyl acetate/methanol; M.P. 146 C., 8:174 g./l.

The following were similarly prepared:

4,4-bis-[n-propyloxy-(1)]-1,1'-binaphthyl, M.P. 194 C., S=25.2 g./l.

4,4-bis-[n-butyloxy-(1)]-1,1-binaphthyl, M.P. 184 C., S=79 g./l.

4,4-bis- [n-amyloxy 1 -1,l'-binaphthyl, M.P. 177 C., S=28.5 g./l. 4,4-bis-[n-hexyloxy-(1)]-l,l'-binaphthyl, M.P. 161 C., S=29.5 g./l.

4,4'-bis-[n-nonyloxy-(1)]-1,1-binaphthyl, M.P. 141 C., S=103 g./l.

4,4-bis-[n-decyloxy-(1)]-1,l'-binaphthyl, M.P. 136 C.,

S=150 g./l.

4,4-bis-[n-undecyloxy-(l)]-l,l"-binaphthyl, M.P. 133 (2., s=94 g./l.

4,4'-bis-[n-d0decyloxy-(1)]-1,1'-binaphthyl, M.P. 131 C., S=101 g./l.

4,4-bis-[n-tetradecyloxy-(1)] 1,1 binaphthyl, M.P. 129 C., S=47 g./l.

4,4-bis-[3-methyl-butyloxy-(1 -1,1'-binaphthyl, M.P. 214 C., S=17.9 g./l.

4,4 bis-[4-methylamyloxy-(1)]-l,l'-binaphthyl, M.P. 197 C., S=20.2 g./l.

4,4-bis-[2-hexyldecyloxy-( 1)] 1,1 binaphthyl, oil, S==eo.

4,4'-bis-[3-oxamyloxy-(1)]-1,1-binaphthyl, M.P. 160 0., 8:55 g./1.

4,4-bis-[3-(octadecyl)-heneicosene 3 yloxy-(1)]-1, 1'-binaphthyl.

4,4-bis-[2,2,4-trimethylamyloxy-(1)]-1, 1'-binaphthyl.

4,4-bis- [3,6-dioxaoctyloxy-( 1 ]-1,1-binaphthyl.

4,4-bis-[3,6,9-trioxaundecyloxy--( 1 ]-1,1'-binaphthyl.

3,3'-dimethyl-4,4'-bis [3 methylbutyloxy-(l)]-1,1- binapthyl.

3,3'-dimethyl-4,4-bis-[3-oxaamyloxy-( 1)] 1,1 binaphthyl.

4,4-dimethoxy 3,3',5,5,6,6 hexamethylyl-1,1'-binaphthyl.

EXAMPLE 12 (a) 112 g. 1-hydroxy-4-bromonaphthalene are dissolved in as little alcohol as possible and then combined with an alcoholic solution of 60 g. potassium hydroxide. Following the addition of 445 g. benzenesulfonic acid-(2- tetradecyD-octadecyl-(1)-ester, the mixture is refluxed for 5 hours. The alcohol is largely distilled oif, then worked up with water/ether. The resultant 1-[2-(tetradecyl)-octadecycloxy-(1)]-4-bromonaphthalene is purified by molecular distillation. The compound has a waxy consistency.

(b) A Grignard solution of 67 g. of the bromonaphthylether obtained according to Example 12(a) is caused to react with 7.5 g. bicyclohexyl-4,4"dione (Makromolekulare Chemie, vol. 37 [1960], p. 211). The carbinol thus formed can be dehydrated, without further purification, with oxalic acid in dioxane (Makromolekulare Chemie, vol. 42 [1961], p. 177). The resultant 4,4-bis- [1-(Z-tetradecyl)-octadecyloxy (1) 1,1,2,2',3,3,6,6'- octahydrobiphenyl is isolated by preparative layer chromatography. The compound is of a waxy consistency and has no precise melting point.

(c) 13 g. of the octahydrobiphenyl derivative obtained according to Example 12(b) is boiled for 48 hours with 12 g. chloranil in 250 ml. xylene. On cooling, it is filtered off from the precipitated tetrachlorohydroquinone. The dark brown filtrate is treated with alkaline dithionite solution until the aqueous phase is colorless. The previously dried xylene solution is chromatographed over a mixture of powdered potassium hydroxide and aluminum oxide.

The isolation of the 4,4-blS-[1-(2 f6lll'3d6CYD-Odfldecyloxy-(l)]-biphenyl is carried out with the aid of the preparative layer chromatography on silica gel with nhexane/benzene/chloroform as the elution agents. The compound is waxy with a softening point of about C. The compound is very readily soluble in homopolar solvents.

The preceding examples can be repeated with similar success by substituting the generically and specifically described reactants and operating conditions of this invention for those used in the preceding examples.

From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. Consequently, such changes and modifications are properly, equitably, and intended to be, within the full range of equivalence of the following claims.

3,600,445 15 16 What is claimed is: OTHER REFERENCES 1. A 4,4'-bis-[R-oxy(1)]-1,1'-binaphthy1 wherein R is alkyl of 3-14 carbon atoms, 3-0Xaarnyl, 3-(octadecyl)- et Jour' Chem" 22 (1957) heneicosene-3-y1, 3,6-dioxaoctyl, or 3,6,9-trioxaundecy1. d 1 h 2. A compound as defined by claim 1 wherein said 5 f gg gigz Amer C VOL 79 (1957) Compound is 4i4"bis'[n'octyloxy'(l)ll'lll'binaphthyl' Stjernst-rom, Acta Chemica Scandinavica, v01. 14

References Cited (1960) 1274-1278 UNITED STATES PATENTS BERNARD HELFIN, Primary Examiner 2,301,206 11/1942 France et al 260613 10 US. Cl. X.R. 2,566,357 9/1951 Orchin et a1. 260-613X 3,231,629 1/1966 McCall et a1. 260'613X 250430; 262 301'2; 668 

